2. FIELD OF THE INVENTION
The present invention relates to a manipulator and, more particularly, to a remote controlled manipulator which is suited for various tasks in places which are not easily accessible to operators.
2. Description of the Prior Art
Japanese Patent Publication No. 37307/1972 discloses a known manipulator which makes use of wire ropes for transmitting the driving power, while Japanese Patent Laid-Open Publication No. 73463/1977 discloses a manipulator in which concentric driving cylindrical tubes are used for power transmission. In either case, the power transmission means extends through an interior of the manipulator arm and is connected to the respective shafts for articulating the adjacent arm sections. Therefore, the disassembly of the manipulator articulate portion for the purpose of, for example, inspection requires demounting and remounting of the power trnamsission means onto the articulate portion, which makes the work difficult and time-consuming.
Japanese Patent Laid-Open Publication No. 6272/1979 discloses a manipulator composed of a plurality of modules each of which can be detachably onto the next one without disassembly of other modules in order to improve the maintainability thereof. This publication, however, discloses merely the basic concept for a module-type manipulator constituted by detachable modules, and fails to disclose practical and specific means for embodying such module mounting and demounting.
The operation rate of the manipulator used in a remote controlled work in places where the operators do not have access to readily, e.g., a high radioactive level area in a nuclear power plant, underwater, cosmic space and so forth, is affected by the maintainability of the manipulator itself. In particular, in a high radioactive level area, the manipulator requires to be assembled and disassembled in a short time. The task in such area, however, is quite severe and difficult even for the experts.
In general, all of arm sections, articulate mechanisms, and power transmission means incorporated in a manipulator are changed according to the degree of freedom thereof and/or the intended use thereof. This in turn requires the articulate portions to be designed and constructed separately and independently. Consequently, the cost of the manipulator is greatly affected by the number of articulates.
In case that it is required to modify an existing manipulator so as to increase arm flexibility by increasing the number of degree of freedom, e.g., in the case where the manipulator is required to extend to an object by detouring or clearing an obstacle. Judging from the degree of freedom, such modification, however, becomes materially equivalent both in difficulty and cost to the designing and the manufacturing of an entirely new manipulator having a different construction, which undesirably limits the adaptability of the manipulator to various specific working demands.
On the other hand, the module-type manipulator composed of modules each of which can be detachably mounted onto the next one suffers from the following disadvantage in respect of the maintainability thereof. Namely, the cost of the manipulator is raised undesirably because of the necessity for the preparation of modules for maintaining the respective detachable modules. In addition, the provision of a plurality of power transmission lines, such as wire ropes or drive tubes, in the arm causes various types of inconvenience, e.g. an increase in the weight, complication in the construction and difficulties in the maintenance due to an increase of coupling elements between adjacent modules.